JP2007120417A - Piping vibration suppressing device for fuel supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piping vibration suppressing device for a fuel supply system capable of compatibly establishing reduction of manufacturing cost and quietness by sufficiently suppressing vibration of return piping without adding an apparatus of a complicated structure. <P>SOLUTION: Fuel pumped from a fuel supply pump 8 is supplied to a delivery pipe 3 through supply piping 7. A pressure regulator 10 regulating fuel pressure therein at constant pressure is provided in the delivery pipe 3, and surplus fuel discharged from the pressure regulator 10 is returned to a fuel tank 1 through the return piping 11. An orifice 13 is provided on an outlet 12 of the return piping 1 which is an open end, in such a fuel supply system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pipe vibration suppressing device that is used in a fuel supply system of an internal combustion engine such as a vehicle and suppresses vibration due to pulse pressure of a return pipe.

As a fuel supply system for an internal combustion engine, there is known a system that supplies fuel to a plurality of injectors while pressure-feeding fuel to a delivery pipe by a fuel supply pump and adjusting a fuel pressure in the delivery pipe to a set pressure by a pressure regulator. . In the case of this system, the pressure regulator is provided in the middle of the delivery pipe or the supply pipe so as to return the surplus fuel to the fuel tank through the return pipe.
JP-A 61-149567 Japanese Patent Laid-Open No. 9-195872

  However, in this general fuel supply system, when the length of the return pipe becomes long, the valve vibration of the pressure regulator may become close to the eigenvalue of the pulse pressure vibration in the return pipe depending on the operating conditions. There is a possibility that the resonance of the return pipe using the pulse pressure due to vibration as an excitation force may occur.

For this reason, conventionally, as a countermeasure, an elastic tube such as an orifice or a rubber tube is provided in the vicinity of the pressure regulator to suppress vibration of the return pipe.
However, this measure may not provide a sufficient effect depending on operating conditions, and in that case, an expensive pulsation damper must be attached to the delivery pipe or the like.

  Accordingly, the present invention provides a pipe vibration suppression device for a fuel supply system that can sufficiently suppress vibration of a return pipe without adding expensive equipment, and can achieve both reduction in manufacturing cost and quietness. It is something to try.

In order to achieve the above-mentioned object, the invention described in claim 1 is configured to pump from a fuel supply pump (for example, a fuel supply pump 8 in an embodiment described later) through a supply pipe (for example, a supply pipe 7 in an embodiment described later). A delivery pipe (for example, a delivery pipe in an embodiment described later) in which fuel in a fuel tank (for example, a fuel tank 1 in an embodiment described later) is conducted to a plurality of injectors (for example, an injector 4 in an embodiment described later) 3) and a pressure regulator (for example, a pressure regulator 10 in an embodiment described later) for adjusting the inside of the delivery pipe to a constant pressure is provided in the middle of the delivery pipe or the supply pipe. Excess fuel to be discharged is returned to the return pipe (for example, described later) In the fuel supply system that is returned to the fuel tank through the return pipe 11) in the embodiment, in the pipe vibration suppression device that suppresses vibration due to the pulse pressure of the return pipe, the outlet of the return pipe (for example, in an embodiment described later) An orifice (for example, an orifice 13 in an embodiment described later) is provided at the outlet 12).
In this case, pulse pressure vibration occurs in the return pipe with the pressure regulator connection port closed and the return pipe outlet open. However, the vibration reflection at the open return pipe outlet is attenuated by the pipe outlet orifice. .

According to a second aspect of the present invention, the fuel in the fuel tank that is pumped from the fuel supply pump through the supply pipe is supplied to the delivery pipe that is connected to the plurality of injectors, and the delivery pipe or the supply pipe is in the middle. A pressure regulator that regulates the inside of the delivery pipe to a constant pressure, surplus fuel discharged from the pressure regulator is returned to the fuel tank through a return pipe, and a jet pump provided at an outlet of the return pipe ( For example, in a fuel supply system that feeds fuel at a specific position in a fuel tank to the vicinity of the fuel tank by a pumping action of a jet pump 20) in an embodiment described later, vibration due to pulse pressure of the return pipe is suppressed. In the piping vibration suppressing device, in the vicinity of the jet pump of the return pipe And to provide an orifice in the flow side.
In the fuel supply system in which the jet pump is provided at the outlet of the return pipe which is the open end, the vibration reflection at the open end tends to be attenuated by the action of the throttle portion of the jet pump, but it is on the upstream side of the throttle portion in the jet pump. Under the situation where the relief valve operates in an unstable manner, the damping effect of vibration reflection by the jet pump also becomes unstable. An orifice provided upstream of the return pipe near the jet pump generates a vibration reflection damping action at the outlet of the return pipe at the open end, and in addition, causes an unstable vibration reflection damping operation of the relief valve. Functions to stabilize.

In the invention according to claim 3, the fuel in the fuel tank that is pumped from the fuel supply pump through the supply pipe is supplied to the delivery pipe that is conducted to the plurality of injectors, and in the middle of the delivery pipe or the supply pipe, There is provided a pressure regulator that regulates the inside of the delivery pipe to a constant pressure, and surplus fuel discharged from the pressure regulator is formed of a metal pipe and a portion close to the outlet is an elastic pipe (for example, in an embodiment described later) In the fuel supply system that is returned to the fuel tank through the return pipe formed by the elastic pipe 11b), in the pipe vibration suppressing device that suppresses vibration due to the pulse pressure of the return pipe, the metal pipe of the return pipe and Orifice between the boundary of the elastic tube (for example, the boundary m in the embodiments described later) and the pipe outlet It was to be provided.
In this case, if an orifice is provided at the outlet of the return pipe elastic tube, expansion and contraction occurs in the peripheral wall portion of the elastic tube upstream of the orifice due to pulsation, and the pressure fluctuation at the orifice portion is reduced, so that sufficient vibration reflection is attenuated. Although the action cannot be obtained, the damping action of the vibration reflection is improved by providing an orifice between the boundary part of the metal pipe and the elastic pipe in the return pipe and the pipe outlet.

In the invention of claim 4, the fuel in the fuel tank that is pumped from the fuel supply pump through the supply pipe is supplied to a delivery pipe that conducts to a plurality of injectors, and in the middle of the delivery pipe or the supply pipe, A pressure regulator that regulates the inside of the delivery pipe to a constant pressure is provided, and surplus fuel discharged from the pressure regulator is supplied through a return pipe formed of a metal pipe as a main part and an elastic pipe as a part close to the outlet. In the fuel supply system which is returned to the tank and further supplies fuel at a specific position in the fuel tank to the vicinity of the fuel tank by a pumping action of a jet pump provided at the outlet of the return pipe. In the pipe vibration suppressing device for suppressing vibration due to pulse pressure, the metal pipe and the elastic From the boundary portion of the tube it was provided with orifices until the jet pump.
In this case, the orifice provided between the boundary between the metal tube and the elastic tube and the jet pump reduces the elastic deformation of the upstream peripheral wall of the elastic tube, so that the vibration at the orifice outlet of the return pipe which is the open end is reduced. It is possible to effectively obtain the reflection attenuation action and to stabilize the vibration reflection attenuation action caused by the restriction of the jet pump.

Further, the invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein a second orifice (for example, a second in an embodiment described later) is provided in the vicinity of the pressure regulator of the return pipe. An orifice 30) was provided.
In this case, in addition to the damping effect of the vibration reflection by the exit side orifice of the return pipe and the jet pump, the fluctuation of the return fuel discharge amount of the pressure regulator is reduced by the second orifice, so that the vibration is generated on the closed end side. The vibration suppression action of the pulse pressure comes to work.

The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein an elastic tube or a bellows tube (for example, a bellows tube 31 in an embodiment described later) is provided in the vicinity of the pressure regulator of the return pipe. ).
In this case, in addition to the damping action of the vibration reflection by the orifice on the outlet side of the return pipe and the jet pump, the action of suppressing the vibration force on the closed end by the elastic pipe and the bellows pipe in the vicinity of the pressure regulator works. Further, when the temperature is high, reduced-pressure boiling is likely to occur immediately below the pressure regulator, but the orifice on the outlet side of the return pipe increases the back pressure in the return pipe, thereby suppressing the reduced-pressure boiling.

  According to the first aspect of the present invention, the vibration reflection at the return pipe outlet which is the open end can be attenuated by the orifice, so that the resonance of the return pipe is effectively suppressed while having an extremely simple structure. Can do.

  According to the second aspect of the present invention, the unstable operation of the relief valve in the jet pump can be reduced by the orifice provided on the upstream side of the return pipe in the vicinity of the jet pump. However, it is possible to effectively reduce the pulse pressure in the return pipe by the throttle portion in the jet pump and the orifice itself.

  According to the invention described in claim 3, since the orifice is provided between the boundary between the metal pipe and the elastic pipe and the pipe outlet in the return pipe, the influence of expansion and deformation of the peripheral wall portion of the elastic pipe is affected. It becomes difficult to act on the orifice, and the pulse pressure in the return pipe can be effectively reduced while having an extremely simple structure.

  According to the invention described in claim 4, since the orifice is provided between the boundary portion between the metal pipe and the elastic pipe and the jet pump in the return pipe, the elastic deformation of the upstream peripheral wall of the orifice is reduced. As a result, the damping action of the vibration reflection by the orifice becomes effective, and the damping action of the vibration reflection by the orifice of the jet pump can be obtained stably, and the resonance of the return pipe is effective despite the extremely simple structure. Can be suppressed.

  According to the fifth aspect of the invention, in addition to the damping action of the vibration reflection by the orifice on the outlet side of the return pipe and the jet pump, the action of suppressing the vibration force on the closed end side by the second orifice works. The resonance of the return pipe can be more effectively suppressed by the synergistic action.

According to the sixth aspect of the present invention, in addition to the action of damping the vibration reflection by the orifice on the outlet side of the return pipe and the jet pump, the action of suppressing the vibration force by the elastic tube and the bellows tube in the vicinity of the pressure regulator works. The resonance of the return pipe can be more effectively suppressed by these synergistic functions.
In addition, since the orifice on the outlet side of the return pipe functions to increase the back pressure in the return pipe, it suppresses the reduced pressure boiling directly under the pressure regulator at high temperatures without causing an increase in manufacturing cost, resulting in reduced pressure boiling. It is possible to prevent generation of fuel flow noise.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings of the embodiments, the same parts are denoted by the same reference numerals.
First, the first embodiment shown in FIG. 1 will be described. This embodiment is an embodiment of the invention according to claim 1, and FIG. 1 shows a schematic configuration of a fuel supply system used in an internal combustion engine for a vehicle.
In FIG. 1, 1 is a fuel tank, 2 is a fuel injection device for an internal combustion engine including a delivery pipe 3 and a plurality of injectors 4, 5 is a battery, and 6 is a control unit (ECU). A fuel supply pump 8 for supplying the fuel in the fuel tank 1 to the delivery pipe 3 through the supply pipe 7 is installed in the fuel tank 1. The fuel supply pump 8 is connected to a power relay 9 and is started when the power is turned on. Further, the delivery pipe 3 is provided with a pressure regulator 10 for adjusting the pressure of the fuel pumped from the fuel supply pump 8 to a set pressure. It is designed to return inside. In this embodiment, the pressure regulator 10 is provided in the delivery pipe 3, but the pressure regulator 10 may be provided in the middle of the supply pipe 7.

  In this embodiment, the return pipe 11 is basically formed of a metal pipe except for a part near the connection with the pressure regulator 10, and is set at the end on the outlet 12 side facing the fuel tank 1. A diameter orifice 13 is provided. In the figure, reference numerals 7a and 11a denote elastic tube portions such as rubber tubes. In the figure, reference numeral 26 denotes a filter connected to the suction part of the fuel supply pump 8, and reference numeral 23 denotes the inside of the fuel tank 1 so as to surround the suction part of the fuel supply pump 8 and the outlet 12 of the return pipe 11. The chamber provided in is shown.

  In this fuel supply system, when the power is turned on, the fuel supply pump 8 is started, the fuel in the fuel tank 1 is pumped to the delivery pipe 3 through the supply pipe 7, and the pressure regulator 10 adjusts the pressure to the set pressure. Fuel is supplied from the delivery pipe 3 to the injector 4. At this time, in the pressure regulator 10, surplus fuel is returned into the fuel tank 1 through the return pipe 11.

  The fuel flow through the return pipe 11 tries to cause resonance of the return pipe 11 by using the pulse pressure generated by the return fuel discharge amount fluctuation accompanying the valve vibration of the pressure regulator 10 as an oscillating force. However, in this fuel supply system, since the orifice 13 is provided at the outlet 12 portion of the return pipe 11 whose main portion is formed of a metal pipe, the vibration reflection at the outlet 12 portion which is the open end is effective by the orifice 13. As a result, resonance in the tube is greatly suppressed.

  A in the graph in FIG. 7 shows the state of pressure fluctuation when no orifice is specially provided in the return pipe, and a in FIG. 7 shows the case where the orifice is provided only on the inlet side of the return pipe (prior art). (B) shows the state of pressure fluctuation, and b shows the state of pressure fluctuation when the orifice 13 is provided at the outlet 12 of the return pipe 11 (in the case of this embodiment). As is apparent from this graph, when the orifice 13 is provided at the outlet 12 of the return pipe 11, the resonance peak amplitude can be reduced by about 50% compared to A when no orifice is provided.

  Hereinafter, each embodiment (second to sixth embodiments) corresponding to claims 2 to 6 will be described focusing on differences from the first embodiment.

  In the second embodiment shown in FIG. 2, the jet pump 20 that transfers the fuel outside the chamber 23 in the fuel tank 1 to the vicinity of the fuel supply pump 8 using the flow rate of the fuel returned from the return pipe 11 returns. An orifice 13 is provided at an outlet 12 portion of the pipe 11, and an upstream position near the jet pump 20 in the return pipe 11. The jet pump 20 includes a main body 22 having a throttle for generating negative pressure and a fuel discharge port (not shown) disposed in a chamber 23, and an end of a fuel transfer pipe 25 connected to the suction port of the main body 22. The portion is disposed outside the chamber 23 via the filter 24.

  In this embodiment, the orifice 13 disposed upstream in the vicinity of the jet pump 20 restricts the vicinity of the outlet 12 and always stabilizes the operation of the relief valve 21 in the jet pump 20. For this reason, the restriction of the jet pump 20 at the outlet 12 of the return pipe 11 functions stably, and the orifice 13 itself also attenuates the vibration reflection, so that the vibration reflection at the pipe end is efficiently attenuated. As a result, the resonance of the return pipe 11 is greatly suppressed. C in FIG. 7 shows the state of pressure fluctuation when the orifice 13 is provided upstream of the return pipe 11 in the vicinity of the jet pump 20 (in the case of this embodiment), as is apparent from this graph. Compared with A when no orifice is provided, the amplitude of the resonance peak can be reduced by about 40%.

  In the third embodiment shown in FIG. 3, the portion near the outlet 12 of the return pipe 11 is formed of an elastic tube 11b such as rubber, and the orifice 13 is formed from the boundary portion m between the metal tube 11c and the elastic tube 11b. The point provided between the outlets 12 is different from that of the first embodiment.

  In this embodiment, when the orifice 13 is provided at the outlet 12 of the return pipe 11, the pressure fluctuation is less likely to act on the orifice 13 due to the expansion and contraction action of the peripheral wall of the elastic tube 11 b, and a stable throttling effect by the orifice 13 is obtained. In order to improve the possibility of being lost, the arrangement of the orifices 13 is set as described above. That is, in this embodiment, by reducing the arrangement of the orifice 13 from the outlet 12 of the elastic tube 11b to the boundary m side of the metal tube 11c and the elastic tube 11b, the reduction effect of the orifice 13 due to the expansion and contraction of the elastic tube 11b is reduced. Less.

  In the fourth embodiment shown in FIG. 4, the portion near the outlet 12 of the return pipe 11 is formed of an elastic tube 11b made of rubber or the like, and the orifice 13 extends from the boundary portion m between the metal tube 11c and the elastic tube 11b. The point provided between the jet pump 20 and the second embodiment is different from that of the second embodiment.

  In this embodiment, similarly to the third embodiment, the arrangement of the orifice 13 is shifted from the outlet 12 of the elastic tube 11b to the boundary portion m side of the metal tube 11c and the elastic tube 11b, whereby the orifice 13 due to the expansion and contraction of the elastic tube 11b. Thus, the reduction effect of the vibration reflection by the restriction of the jet pump 20 and the orifice 13 can be obtained more reliably.

In the fifth embodiment shown in FIG. 5, the second orifice 30 is further provided in the vicinity of the outlet of the pressure regulator 10 in the return pipe 11 (in the vicinity of the inlet of the return pipe 11) compared to the fuel supply system of the fourth embodiment. It is provided. In this embodiment, the damping effect of vibration reflection on the open end side by providing the orifice 13 on the upstream side in the vicinity of the jet pump 20 in the elastic pipe 11b of the return pipe 11, and on the inlet side of the return pipe 11 The effect of suppressing the excitation force on the closed end side by providing the second orifice 30 can be enjoyed synergistically.
Of course, in the case of the first to third embodiments, the same synergistic effect can be obtained by providing the second orifice 30 in the vicinity of the outlet of the pressure regulator 10. D in FIG. 8 shows the state of pressure fluctuation when the second orifice 30 is further provided in the vicinity of the outlet of the pressure regulator 10 in the system of the first embodiment, which is apparent from this graph. In comparison with the case where the orifices 13 and 30 are provided independently on the outlet side of the return pipe 11 and in the vicinity of the outlet of the pressure regulator 10 (near the inlet of the return pipe 11) (a and b in the figure), respectively. The peak amplitude can be significantly reduced (approximately 87% reduction relative to a).

In the sixth embodiment shown in FIG. 6, a bellows tube is provided in the vicinity of the pressure regulator 10 (a portion directly below the second orifice 30) of the return pipe 11 in addition to the fuel supply system of the fifth embodiment. 31 is provided. In this embodiment, the damping effect of the bellows tube 31 works more synergistically with the effect of the fifth embodiment, and the resonance of the return pipe 11 can be further effectively reduced.
Further, in this fuel supply system, the orifice 13 is arranged on the outlet side of the return pipe 11, and the back pressure on the inlet side of the return pipe 11 is increased, so that the reduced pressure boiling that is likely to occur directly under the pressure regulator 10 at a high temperature. Can be reliably suppressed by this back pressure. Therefore, it is possible to prevent the generation of fuel flow noise due to boiling under reduced pressure without causing an increase in manufacturing cost.

FIG. 9 shows the characteristics of the pulsation amplitude in the return pipe 11 when the throttle diameter of the outlet 12 of the return pipe 11 (or the diameter of the orifice 13) is changed. The pulsation characteristics when the orifice 13 is arranged independently at the outlet 12 of the return pipe 11 are shown, and (B) in the figure shows the pulsation when the orifices 13 and 30 are arranged at the outlet 12 and the inlet of the return pipe 11, respectively. The characteristics are shown. Further, m in the figure is a pressure amplitude threshold value that facilitates suppression of vibration and noise within a range smaller than the value.
As apparent from this figure, when the orifices 13 and 30 are provided at the outlet 12 and the inlet of the return pipe 11 as compared with the case where the orifice 13 is provided alone at the outlet 12 of the return pipe 11, the outlet 12 The throttle diameter on the side (the diameter of the orifice 13) can be increased.

  In addition, this invention is not limited to the said embodiment, A various design change is possible in the range which does not deviate from the summary.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows 1st Embodiment of this invention. The schematic block diagram which shows 2nd Embodiment of this invention. The schematic block diagram which shows 3rd Embodiment of this invention. The schematic block diagram which shows 4th Embodiment of this invention. The schematic block diagram which shows 5th Embodiment of this invention. The schematic block diagram which shows 6th Embodiment of this invention. FIG. 6 is a diagram showing the relationship between the fuel pressure amplitude and the engine speed according to the orifice installation position. FIG. 6 is a diagram showing the relationship between the fuel pressure amplitude and the engine speed according to the orifice installation position. FIG. 6 is a diagram showing the relationship between the outlet throttle diameter and the pulsation amplitude when an orifice is provided only on the outlet side of the return pipe and when an orifice is provided on both the outlet side and the inlet side of the return pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel tank 3 ... Delivery pipe 4 ... Injector 7 ... Supply piping 8 ... Fuel supply pump 10 ... Pressure regulator 11 ... Return piping 13 ... Orifice 30 ... Second orifice 31 ... Bellows tube

Claims (6)

The fuel in the fuel tank that is pumped from the fuel supply pump through the supply pipe is supplied to the delivery pipe that is connected to the plurality of injectors, and the delivery pipe is adjusted to a constant pressure in the middle of the delivery pipe or the supply pipe. In a fuel supply system in which a pressure regulator is provided, and surplus fuel discharged from the pressure regulator is returned to the fuel tank through a return pipe, and in a pipe vibration suppression device that suppresses vibration due to pulse pressure of the return pipe,
An apparatus for suppressing vibration of piping in a fuel supply system, wherein an orifice is provided at an outlet of the return pipe. The fuel in the fuel tank that is pumped from the fuel supply pump through the supply pipe is supplied to the delivery pipe that is connected to the plurality of injectors, and the delivery pipe is adjusted to a constant pressure in the middle of the delivery pipe or the supply pipe. A pressure regulator is provided, and surplus fuel discharged from the pressure regulator is returned to the fuel tank through the return pipe, and further, fuel at a specific position in the fuel tank is obtained by the pumping action of the jet pump provided at the outlet of the return pipe. In a fuel supply system that supplies fuel to the vicinity of the fuel tank, wherein the vibration suppression device suppresses vibration due to pulse pressure of the return pipe,
An apparatus for suppressing pipe vibration in a fuel supply system, wherein an orifice is provided on the upstream side of the return pipe in the vicinity of the jet pump. The fuel in the fuel tank that is pumped from the fuel supply pump through the supply pipe is supplied to the delivery pipe that is connected to the plurality of injectors, and the delivery pipe is adjusted to a constant pressure in the middle of the delivery pipe or the supply pipe. A pressure regulator is provided, and surplus fuel discharged from the pressure regulator is returned to the fuel tank through a return pipe formed of a metal pipe and a part close to the outlet of the main part. In the pipe vibration suppressing device for suppressing vibration due to the pulse pressure of the return pipe,
A piping vibration suppression device for a fuel supply system, wherein an orifice is provided between a boundary portion between a metal tube and an elastic tube and a piping outlet in the return piping. The fuel in the fuel tank that is pumped from the fuel supply pump through the supply pipe is supplied to the delivery pipe that is connected to the plurality of injectors, and the delivery pipe is adjusted to a constant pressure in the middle of the delivery pipe or the supply pipe. A pressure regulator is provided, and surplus fuel discharged from the pressure regulator is returned to the fuel tank through a return pipe formed of a metal pipe at the main part and an elastic pipe near the outlet. In a fuel supply system that feeds fuel at a specific position in a fuel tank to the vicinity of the fuel tank by a pumping action of a jet pump provided at the outlet of the pipe, pipe vibration that suppresses vibration due to pulse pressure of the return pipe In the suppression device,
A piping vibration suppression device for a fuel supply system, wherein an orifice is provided between a boundary portion between a metal pipe and an elastic pipe in the return pipe and the jet pump.   The pipe vibration suppression device for a fuel supply system according to any one of claims 1 to 4, wherein a second orifice is provided in the vicinity of the pressure regulator of the return pipe. The piping vibration suppression device for a fuel supply system according to any one of claims 1 to 5, wherein an elastic tube or a bellows tube is provided in the vicinity of the pressure regulator of the return pipe.

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